This phase II Pediatric MATCH trial studies how well erdafitinib works in treating patients with solid tumors, non-Hodgkin lymphoma, or histiocytic disorders that have spread to other places in the body and have come back or do not respond to treatment with FGFR mutations. Erdafitinib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth.

This phase II Pediatric MATCH trial studies how well larotrectinib works in treating patients with solid tumors, non-Hodgkin lymphoma, or histiocytic disorders with NTRK fusions that have spread to other places in the body and have come back or do not respond to treatment. Larotrectinib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth.

This partially randomized phase III trial is studying maintenance chemotherapy to see how well it works compared to observation following induction chemotherapy and radiation therapy in treating young patients with newly diagnosed ependymoma. Drugs used in chemotherapy, such as vincristine sulfate, carboplatin, cyclophosphamide, etoposide, and cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving more than one drug (combination chemotherapy) may kill more tumor cells. Radiation therapy uses high-energy x-rays to kill tumor cells. Specialized radiation therapy that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue. Giving chemotherapy with radiation therapy may kill more tumor cells and allow doctors to save the part of the body where the cancer started.

This phase II Pediatric MATCH trial studies how well olaparib works in treating patients with solid tumors, non-Hodgkin lymphoma, or histiocytic disorders with defects in deoxyribonucleic acid (DNA) damage repair genes that have spread to other places in the body and have come back or do not respond to treatment. Olaparib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth.

This phase II Pediatric MATCH trial studies how well palbociclib works in treating patients with Rb positive solid tumors, non-Hodgkin lymphoma, or histiocytic disorders with activating alterations (mutations) in cell cycle genes that have spread to other places in the body and have come back or do not respond to treatment. Palbociclib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth.

This phase II Pediatric MATCH trial studies how well PI3K/mTOR inhibitor LY3023414 works in treating patients with solid tumors, non-Hodgkin lymphoma, or histiocytic disorders with TSC or PI3K/MTOR mutations that have spread to other places in the body and have come back or do not respond to treatment. PI3K/mTOR inhibitor LY3023414 may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth.

This Pediatric MATCH screening and multi-sub-study phase II trial studies how well treatment that is directed by genetic testing works in pediatric patients with solid tumors, non-Hodgkin lymphomas, or histiocytic disorders that have progressed following at least one line of standard systemic therapy and/or for which no standard treatment exists that has been shown to prolong survival. Genetic tests look at the unique genetic material (genes) of patients' tumor cells. Patients with genetic changes or abnormalities (mutations) may benefit more from treatment which targets their tumor's particular genetic mutation, and may help doctors plan better treatment for patients with solid tumors or non-Hodgkin lymphomas.

This phase II Pediatric MATCH trial studies how well ulixertinib works in treating patients with solid tumors that have spread to other places in the body (advanced), non-Hodgkin lymphoma, or histiocytic disorders that have a genetic alteration (mutation) in a signaling pathway called MAPK. A signaling pathway consists of a group of molecules in a cell that control one or more cell functions. Genes in the MAPK pathway are frequently mutated in many types of cancers. Ulixertinib may stop the growth of cancer cells that have mutations in the MAPK pathway.

This phase II Pediatric MATCH trial studies how well vemurafenib works in treating patients with solid tumors, non-Hodgkin lymphoma, or histiocytic disorders with BRAF V600 mutations that have spread to other places in the body and have come back or do not respond to treatment. Vemurafenib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth.

This phase II Pediatric MATCH trial studies how well tazemetostat works in treating patients with solid tumors, non-hodgkin lymphoma, or histiocytic disorders that have spread to other places in the body and have come back or do not respond to treatment and have EZH2, SMARCB1, or SMARCA4 gene mutations. Tazemetostat may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth.

RATIONALE: Specialized radiation therapy that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Giving chemotherapy before surgery may shrink the tumor so that it can be removed during surgery.

PURPOSE: Phase II trial to determine the effectiveness of specialized radiation therapy either alone or after chemotherapy and second surgery in treating children who have undergone surgery for localized ependymoma.